HAIRY SEEDS 



257 



they do not, under these conditions, grow well or 

 healthily ; the simple reason being that they have not 



enough light, nor 

 probably enough 

 water and food, be- 

 cause these are 

 taken by the strong- 

 er roots of the larger 

 trees. It will, there- 

 fore, obviously be 

 on the whole better 

 for the plant that 

 springs up from the 

 seed if it is carried 

 far away from its 

 parent tree. This 

 then is the purpose 

 of wings on seeds. 



There are plants, 



again, whose seeds have a tuft of long fine hairs at 

 one end. Examples of this are common enough, e.g. 

 CALOTROPIS GIGANTEA, which grows on sandy sea- 

 shores and everywhere inland on sandy and dry hot 

 place in India, CYNANCHUM PAUCIFLORUM, CARAL- 

 LUMA ADSCANDENS, and many others of the family 



ASCLEPIADACE^ (fig. 58). Also NERIUM ODORUM 

 commonly grown in gardens, WRIGHTIA TOMENTOSA 

 (fig. 59), and some others of the family APOCYNACE^E. 



In GOSSYPIUM, the Cotton plant, and other MALVA- 

 CEAE hairs grow out from the whole surface of the 

 seed. The effect of these hairy growths is the same 

 as that of the wing in the other cases, the seed is 

 17 



FIG. 58 

 D^EMIA EXTENSA. Br. 



